"This is a tragic incident," Serpas said. "A man's life is lost. ...We will investigate this thoroughly and completely."

Serpas said a loaded .45-caliber gun was found next to the dead man.

Two 2nd District officers arrived on the scene after they received a call about shoplifting at a convenience store, Serpas said.

"Only one officer fired," Serpas said, declining to specify how many shots were fired.

Serpas did not release the officer's name, but he said that the officer who shot the man has been placed on desk duty as the investigation into the shooting continues. The Orleans Parish District Attorney's Office will review the shooting, Serpas said.

"In general terms, an officer would not open fire unless he feels he is under a threat to his life," he said. "A crime like this reminds us that there is no such thing as a routine police call."

Neither Serpas nor the Orleans Parish coroner's chief investigator John Gagliano released the identify of the victim on Sunday afternoon.

"I have met with (the officer), and we are confident that a full and complete investigation will justify his actions," said attorney Eric Hessler, who is representing the officer.

Serpas said the NOPD Public Integrity Bureau's Force Investigation Team will be supervising the investigation into the shooting and that Public Integrity Bureau detectives and the Independent Police Monitor immediately were called to the scene. Moreover, he said, the Force Investigation Team will work closely with the FBI agents who are housed within the Public Integrity Bureau.

The gun found next to the man was taken to Baton Rouge, where State Police forensic experts are running it through DNA testing, Serpas said, and the officer's gun has been confiscated for examination.

"It is always a sad day when there is a loss of life," Serpas said. "I spoke with the man's father on the scene, and then went to the man's mother's home with Deputy Chief Arlinda Westbrook to speak with the mother privately.

"I made a promise to the parents, as I do to the family of the officer involved, that we will investigate this matter thoroughly and completely to get an accurate account of exactly what took place."

Westbrook heads up the Public Integrity Bureau. The NOPD asks anyone with information about the incident to call the Force Investigation Team at 504.685.6800 or CrimeStoppers at 504.822.1111.

"Many members of the community mentioned that there are videos of the incident, and we implore them to come forward and assist in making sure that all questions are answered," Independent Police Monitor Susan Hutson wrote in a statement released on Sunday afternoon.